1. Field of the Invention
The invention concerns a process and an apparatus for the opening of the bloodstream in unbeheaded flat-fish in the region of their abdominal cavities for the purpose of the bleeding.
2. Description of Prior Art
The blood-letting of freshly caught fish is a process which is prescribed by law in some countries, but basically is, however, of importance when it is desired to attain products of highest quality. To bring this effect fully to bear, it is necessary that the opening of the bloodstream take place immediately after the catching. This is usually achieved by an incision, which is conventionally performed by hand in the case of flat-fish, the incision being made from the belly side of the fish through the gill cavity up to the back bone. Such manual operation presents, on the one hand, the problem that sufficient personnel capacity must be present on board in order to be able to perform this operational step in the available time. On the other hand the fish suffers in its shape stability by such a cut, particularly since a precise cut application cannot be attained by manual means. Moreover, such manually-applied cut results in the difficulty that a mechanized further processing of the fish is made more difficult, if not impossible, because its exact alignment oriented at the outer contours, which is required for mechanical processing, it not possible. Because of these relationships, it has been attempted particularly in the case of flat-fish to attain the bleeding by opening the bloodstream through cutting the tail off. The result is, however, unsatisfactory with respect to the required bleeding time as well as to the degree of bleeding.
From the NL-OS 69 09 615, there is known an apparatus for the gutting of flat-fish, in which the abdominal cavity is opened from the side by means of a hack knife, the throat is severed and the intestines are subsequently sucked away through this incision by means of a suction nozzle. Apart from the fact that this equipment is not designed for the object of the opening of the bloodstream, it is also not suitable for this purpose, because such a function is assured with this cut application only when the flat-fish to be processed is so precisely aligned with respect to the tool that the bloodstream is tangent to the latter. It is open to question that this effect may perhaps result occasionally in the case of a particular fish; however, this known equipment is not usable for an intentional opening of the bloodstream because of the impossibility of such an exact alignment.
In the GB-PS 1 376 624, furthermore, a slaughtering machine is described, in which a tool is lowered from the side onto the flat-fish lying flat and being aligned with respect to their external outline, which tool is provided with stirring vanes, which enter one another in rolling motion and the points of which are constructed as knife blades and cut out the abdominal cavity wall, whereupon the intestines wind themselves around the stirring vanes and are torn out of the abdominal cavity. Here, too, the opening of the bloodstream is not mentioned as an object or intention and is also not to be made certain for the explained reasons.